Although the aviation sector is a relatively small contributor to total greenhouse gas emissions, it is a fast-growing, fossil fuel-intensive transportation mode. Because aviation is a mode for which liquid fuels currently have no practical substitute, biofuels are gaining attention as a promising cleaner alternative. In this paper, we use the GCAM integrated assessment model to develop scenarios that explore the potential impact of biojet fuels for use in aviation in the context of broader climate change mitigation. We show that a carbon price would have a significant impact on the aviation sector. In the absence of alternatives to jetmore » fuel from petroleum, mitigation potential is limited and would be at the expense of aviation service demand growth. However, mitigation efforts through the increased use of biojet fuels show potential to reduce the carbon intensity of aviation, and may not have a significant impact on carbon mitigation and bioenergy use in the rest of the energy system. The potential of biofuel to decarbonize air transport is significantly enhanced when carbon dioxide capture and storage (CCS) is used in the conversion process to produce jet fuels from biomass feedstock.« less

Dissolved oxygen (DO) in rivers is a common environmental problem associated with hydropower projects. Approximately 40% of all FERC-licensed projects have requirements to monitor and/or mitigate downstream DO conditions. Most forms of mitigation for increasing DO in dam tailwaters are fairly expensive. One area of research of the Department of Energy's Hydropower Program is the development of advanced turbines that improve downstream water quality and have other environmental benefits. There is great interest in being able to predict the benefits of these modifications prior to committing to the cost of new equipment. In the case of turbine replacement or modification,more » there is a need for methods that allow us to accurately extrapolate the benefits derived from one or two turbines with better design to the replacement or modification of all turbines at a site. The main objective of our study was to demonstrate a modeling approach that integrates the effects of flow and water quality dynamics with fish bioenergetics to predict DO mitigation effectiveness over long river segments downstream of hydropower dams. We were particularly interested in demonstrating the incremental value of including a fish growth model as a measure of biological response. The models applied are a suite of tools (RMS4 modeling system) originally developed by the Tennessee Valley Authority for simulating hydrodynamics (ADYN model), water quality (RQUAL model), and fish growth (FISH model) as influenced by DO, temperature, and available food base. We parameterized a model for a 26-mile reach of the Caney Fork River (Tennessee) below Center Hill Dam to assess how improvements in DO at the dam discharge would affect water quality and fish growth throughout the river. We simulated different types of mitigation (i.e., at the turbine and in the reservoir forebay) and different levels of improvement. The model application successfully demonstrates how a modeling approach like this one can be used to assess whether a prescribed mitigation is likely to meet intended objectives from both a water quality and a biological resource perspective. These techniques can be used to assess the tradeoffs between hydropower operations, power generation, and environmental quality.« less

China is the world’s largest energy consumer and carbon dioxide (CO2) emitter. China has committed to limit its greenhouse gas emissions. With its heavy reliance on domestic coal resources, China faces an enormous challenge of transitioning its economy to a low-carbon energy mix to achieve long-term climate and local air quality goals. Carbon capture, utilization, and storage (CCUS) is widely recognized as an important option for emissions mitigation. The near-term readiness and cost of CCUS technologies, the sectors and regions of CO2 capture, and the location and adequacy of CO2 storage sites all affect the application of CCUS in China’smore » low-carbon development. This study uses GCAM-China, a global integrated assessment model with details for 31 provinces in China, to examine the role of CCUS as part of China’s climate mitigation strategy over the period of its Nationally Determined Contributions as well as in the transition to deeper emissions reductions toward mid-century. The inclusion of new provincial CO2 storage cost curves gives a more detailed evaluation of where, in terms of geography and sector, and when CCUS deployment in China may take place. The results suggest that the scale of deployment varies depending on socioeconomic development pathways and the level of deployment of other low-carbon technologies. Across provinces and development pathways, early deployment of CCUS occurs within industrial and synthetic fuel production sectors, followed by increased deployment in the power sector by mid-century. Several provinces, such as Shandong, Inner Mongolia, Hebei, and Henan, emerge as particularly important in CCUS deployment, as a result of large CO2 point sources and storage availability. Results indicate that storage resource availability is unlikely to constrain CCUS deployment in most provinces through the end of the century.« less

Mitigating carbon emissions in the current energy system will require fundamental changes of both the energy supply and the energy demand sectors. Previous global model-based analyses, however, have focused mostly on energy supply transformations, while the energy demand sector changes are less well understood. In this study, this knowledge gap is addressed by analysing in detail the projected future energy demand projections, and the required demand-side changes to reach stringent mitigation targets using a suite of integrated assessment models. We examine industry, transport and buildings sector pathways across four models and three different reference scenarios from the Shared-Socioeconomic Pathway frameworkmore » which is used as a set of common future perspectives by the climate research community. The demand side mitigation efforts are compared to a more detailed, sector-specific, technology-oriented assessments of abatement potential based on a literature review for the year 2030. The results indicate that strong emission growth in the industry and transport sector can be attributed to increasing final energy per capita and population growth. In the stringent mitigation scenarios energy efficiency, electrification and switching to low carbon fuel are all required in the short term. In the green growth SSP1 scenario the required emission reduction is significantly less than other scenarios showing that the demand growth and the technology development largely affects the sectors’ mitigation challenge. The technology assessment estimates that in particular in the transport and buildings sector there is a higher potential to reduce demand-side emissions through energy efficiency improvements than currently envisioned in the integrated assessment models.« less

This report forecasts air carrier jet fuel usage by body type for three user defined markets. The model contains options which allow the user to easily change the composition of the future fleet so that fuel usage scenarios can be 'run'. Both Volumes I and II are contained in this report. Volume I describes the structure of the model. Volume II is a computer users manual.